The Problem: Clean 8 inch depth of sludge from a 55,000 gallon underground concrete No. 6 oil storage tank belonging to Heppenstall Steel of Pittsburgh, Pa. in 1954.
The Prescription: Introduced 3 drums of Alken Even-Flo 905 on top of the sludge and a quantity of No. 6 oil equivalent to the amount of sludge present. Agitated with air for 2 days (heating would have improved the speed of results, but heat was not an option for this client). Pumped down all that was possible and again added 3 drums of Alken Even-Flo 905 and agitated again for 2 days.
Results: After 2 days, pumpdown removed 4 inches of the sludge. After a second dose was applied and agitated for 2 days, sludge was removed down to one inch of the bottom of the tank, so seven of eight inches of sludge was removed in four days with 330 gallons of Alken Even-Flo 905. The remaining one inch was below the suction line.
Today we would have prescribed using a sump pump to remove the last one inch of oil-sludge mix and then cleaning and bioremediating the thin coating of oil remaining with Alken Clear-Flo 5100 .